In my case i have two clients. client A sends a message to an address that contains a single non durable and non temporary queue on which Client B has registered its consumer. This queue will be created on client B startup (if it not already exists).

In the common case, that both client are up and running, the message delivery works as expect. But when client B is down during client A sends a message and client B comming up again, the message will be deliverd twice to consumer of client B.